Wouldn't it be great if you didn't have to vote for the least horrible candidate? If you could vote for who you wanted without feeling like you're throwing your vote away?
If we had ranked choice voting, we'd have better legislators in office to start with. And if they used it in the speaker votes this could be resolved already.
The suggestion is that there would still be a Republican speaker, but that a different consensus candidate would win.
That said, in the Raskin/Beyer op-ed that FairVote references, they talk about people being required to list a second choice, which would certainly work but of course isn't required in normal elections.
It's naive to think a consensus candidate would win with STV when they wouldn't with the current system. The majority party controls when the vote is called and if they'd hold until they knew the outcome.
The second choice option is too easy to game. Choose 2 obscure members and you're effectively voting, "Present."